The left-handed Santana underwent surgery in April 2013 to repair his torn shoulder capsule, the second time in three years he had that procedure done. The first time, he missed the entire 2011 season.
Santana, 35, signed a Minor League contract with the O's in March but has yet to appear in a game. He hasn't pitched at any level since August 2012 with the Mets.
The pseudo-callup comes a day after the two-year anniversary of his no-hitter -- June 1, 2012, against the Cardinals.
Santana was a two-time Cy Young Award winner for the Twins (2004, 2006) and a four-time All-Star. He has a lifetime 139-78 record with a 3.20 ERA in more than 2,000 innings across 12 Major League seasons. He is also 12 strikeouts shy of 2,000 for his career.
Tim Healey is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.